After being manufactured, an IC device must be tested functions thereof to assure quality thereof With respect to the testing of IC devices, a conventional approach utilizes a series of test patens to test functions of a tested IC device. By the series of test patens, the designer attempts to emulate all possible conditions under the actual operation environment in the test environment, but it is usually impossible. To date, the conventional approach in which one individual IC device is tested under a series of test patens is still employed in several prior arts, e.g., U.S. Pat. Nos. 4,928,278 and 5,432,797.
However, according to the practical experiences, one IC device, which pass the function test of the conventional approach, may still malfunction under actual operation environment. This cause is that the test patens and fault coverage of the conventional approach cannot accurately emulate whole possible conditions under actual environment. Moreover, for detecting the error point of the malfunctioning IC device, the designer must add other test patens to the series of test patens and then re-test the IC device. The procedure mentioned above is repeated until the error point of the IC device is detected. It is evident that the conventional approach consumes much time and cost, and that the test reliability of the IC device tested by the conventional approach is very low.
Accordingly, an objective of the invention is to provide a rapid and reliable method for testing and debugging an IC device. In particular, the invention provides a method for testing and debugging a first IC device by use of an error-free second IC device. The second IC device is identical to the first IC device, i.e., the first and second IC devices follow the same specification and have the same I/O layout. The method of the invention can detect an error point of one malfunctioning IC device accurately. Furthermore, the I/O history of the malfunctioning IC device ahead and behind of the error point thereof can be monitored. This can provide accurate test result and valuable reference for correction of the malfunctioning IC device.
The concept and spirit of this present invention are applicable to digital and analog types of IC devices.